Radial flow turbine



y 1933- A. LYSHOLM 1,910,845

RADIAL FLOW TURBIfiE Filed Nov. 14. 1930 2 Sheets-Sheet 1 7INV; TO 2 BYMay 23, 1933- A. LYSHOLM Q 1,910,845

RADIAL FLOW TURBINE Filed Nov. 14. 19:50 2 Sheets-Sh et 2 BY "25mmPatented May 23, 1933 UNITED STATES PATENT OFFICE ALF LYSHOLM, OFSTOCKHOLM, SWEDEN, ASSIGNOR 'I O AKTIEBOLAGEI LJ'UNGSTROMS ANGTUBBIN, OF.STOCKHOLM, SWEDEN, A JOINT-STOCK COMPANY RADIAL rLow TURBINEApplication filed- November 14, 1930, Serial No. 495,624, and In SwedenDecember 10, 1.929.

The present invention relates to radial flowvelastic fluid turbinesadapted to oper- .ate against back pressure and provided with a turbinecasing immediately surrounding the radial flow blade system, said casingproviding one or more spiral or volute shaped exhaust chambers extendingaround the full periphery of the outer blade ring of the turbine.

In prior forms of radial .flow turbines, steam is exhausted from theradially outermost blade ring in a radial direction, and

this direction of discharge causes losses due to turbulence and theformation of eddies, because of the necessity of sharply altering thedirection of flow ofthe fluid after it has ence between the point wheresteam is exhausted from the turbine blades and where it is available foruse at a lower pressure stage represents an energy loss which isproduced largelyat the moment when the m0- tive fluid leaves the lastblade row of the turbine. A principal object of the resent invention isto reduce exhaust losses of the above character in radial flow backpressure turbines, and this and other objects, as will hereinafter bemore fully pointed out, are attained by the provision of novel bladingin the last row of turbine blades, which blading is designed to give tothe leaving steam a velocity component in the direction of the outlet oroutlets of the turbine casing. This construction, when combined with acasing of spiral or volute form providing increasing flow area towardthe outlet or outlets of the casing, provides an arrangement such thatthe losses due to turbulent flow and like factors are substantiallyeliminated and a pressure at the outlet of the turbine is maintainedwhich is substantially equal to the pressure at the outlet of the lastor outermost blade row of the turbine.

For a better understanding of the invention, reference may be had to theaccompanying drawings illustrating the invention embodied in a turbinehaving a casing providing a single outlet for motive fluid.

In the drawings:

Fig. 1 is a lon itudinal central section of a radial flow turiineembodying the invention;

Fig. 2' is a transverse section taken through the center of the turbine,parts being omitted for the sake of clearness; and,

Fig. 3 is a diagram illustrating the charactor of the fluid dischargedfrom the outer blade ring of the turbine.

Referring now more particularly to Fig. 1, reference characters 1 and 2designate the oppositely rotating shafts of a double rotary form ofturbine of the known Ljungstrom type. Steam is supplied to the turbinesthrough conduit 3 and flows through themlet chambers 4 and channels 5 inthe turbine rotors to the radial flow blade system 7 of the turbine fromwhich it is discharged to the outlet chamber 8. The outlet chamber 8 ispreferably disposed within an outer turbine'casing 9 and is formed bythe volute shaped casing member 10, which in -the illustrated embodimentextends around the entire circumference of the blade system of theturbine.

As shown in Fig. 2, the casing 10 preferably consists of two parts, 100:and 10b, secured to each other in any suitable manner, as by means offlanges 11 and 12 adapted to be bolted together.

The casing 10 is held in position by means of suitable bolts 15 whichsecure the casing to the flanges 14 on the stationary members 13. Thesebolts-may advantageously be in the form of through bolts, as indicatedin Fig. 1, the central portions of the bolts passing transversely thoughthe chamber 8. These central portions, shown in section in Fig. 2, arepreferably of stream lined cross section and arranged so as to assist 1ndirecting the steam discharged from the blade system toward the outlet.

As will be apparent from Fig. 2, the outer periphery of the volutecasing 10 is arranged, with respect to the outer blade ring of theturbine, so that steam leaving said blade ring is directed so as to havea smooth flow from its point of dischargefrom the blade ring to theoutlet 16 of the volute casing. The outlet 16 is preferably arrangedtangentially of the casing as shown, and it will be apparent that, ifdesired, steam can be taken off from the casing at more than one pointbyproviding additional outlets.

The exhaust conduit 17, with which the outlet 16 communicates, ispreferably supported by means, such as is indicated at 18 and 19, in amanner permitting movement of the exhaust conduit to compensate forexpansion due to temperature differences and the like.

In accordance with the present invention, the shape and arrangement ofthe blades 7 in the last or outermost blade ring is such that the motivefluid is discharged from these blades in a direction having a componentin the direction of discharge flow through the chamber 8.

The manner in which the desired direction of discharge flow from theblade system is accomplished is more clearly illustrated in the diagramof Fig. 3. In this figure, the character of the discharge flow from thelast blade ring of a turbine of the prior art is shown in broken lines,and the direction of the discharge flow in accordance with the presentinvention is shown in full lines. Reference character a designates ablade arrangement for the outer blade ring which is in accordance withthe prior art. lVith this arrangement, the outlet angle a is such that,with a peripheral velocity represented by the vector u and a relativedischarge velocity represented by the vector 'v,

the resultant or a solute discharge velocity will be represented by thevector 0, which is directed radially of the blade system.

In order to avoid the losses through undesirable factors inherent in aturbine in which the motive fluid is exhausted in this manner, the bladem is arranged, in accordance with the present invention, so that theoutlet angle (1 provides a relative discharge velocity represented bythe vector 0 having a value greater than the value of the vector '0, sothat the resultant vector 0 representing the absolute discharge, isdisposed at an angle with respect to a radius vector.

If the vector c is resolved into its radial and peripheral components,it will be seen that, in accordance. with the present invention, thereis provided a radial discharge velocity represented by a and aperipheral 1 dischar e velocity represented by the vector h, t e latterbeing parallel, but opposite in direction, to the velocity vector u IThis velocityvector h represents the'dimotion and value of the dischargeenergy of the motive fluid in the direction-of the outlet of the turbinecasing, and represents a force acting to discharge steam from theturbine. Obviously, the value of the peripheral or tangentialvelocityrepresented by the vector it varies with variations in sizesired flow.

From the foregoing, it will be evident that the motive fluid will, inaccordance with the present invention, have a pressure in the dischargeconduit 17 substantially the same as that in the chamber 8, which is, inturn, substantially the same as the pressure at the point of dischargefrom the last blade row.

By arranging the. blades in the last blade row in the above describedmanner, some loss may be incurred, as compared with a like turbine inwhich the discharge from the last blade row is in radial direction, dueto the greater discharge velocity of the motive fluid when it isdischarged with an appreciable peripheral or tangential component, butthis loss is considerably less than the pressure drop loss in thedischarge casing when the motive fluid is discharged fromt-he last bladerow in the usual radial direction.

It is obvious that, the present invention may be embodied, not only inthe form of apparatus herein shown by way of illustration, but mayalsobe embodied in other specific forms of turbines in which the singlevolute shaped exhaust chamber and outlet, illustrated herein, arereplaced b a plurality of equivalents, each of whic receive and dischare a portion of the total amount of motive uid discharged from the bladesystem.

What I claim is:

1. In a radial flow elastic fluid turbine, a blade system for expandingmotive fluid comprising-a rotor carrying a plurality of blade ringsincluding a blade ring constituting the outermost radial flow blade ringof the turbine, and a casing providing a volute shaped chamber having anoutlet, said outermost blade ring discharging motive fluid to saidchamber and comprising a pluralit of blades each arranged tosimultaneous y discharge motive fluid therefrom with an absolutevelocity havin a peripheral or tangential'component o flow, said flowbeing in the direction of the flow of motive fluid-in said chambertoward the outlet thereof. I

blade system for expanding motive fluid comprising a rotor carrying aplurality of blade rings including a blade rin constituting theoutermost radial flow b ade ring of the turbine, and a casing providinga single volute shaped chamber encircling said outermostblade ring andreceiving motive fluid discharged therefrom, said chamber having anoutlet and said outermost blade ring comprising a plurality of bladeseach arranged to simultaneously discharge motive fluid therefrom with anabsolute velocity having a peripheral or tangential component of flow,said flow being in the direction of the flow of motive fluid in saidchamber toward the outlet thereof.

3. In a radial flow elastic fluid turbine, a blade system for expandingmotive fluid comprising a rotor carrying a plurality of bladeringsincluding a blade ring constituting the outermost radial flow bladering of the turbine, and a casing providing a volute shaped chamberhaving an outlet, said chamber increasing in cross-sectional area towardsaid outlet in a direction opposite the direction of rotation of saidoutermost blade ringand said outermost blade ring comprising a pluralityof blades each arranged to simultaneously discharge motive fluidtherefrom with an absolute velocity having a peripheral or tangentialcomponent of flow,"said flow being in the direction of increasingcross-sectional area of said chamher.

4. In a radial flow elastic fluid turbine, a blade system for expandingmotive fluid .comprising a rotor carrying a plurality of blade ringsincluding a blade ring constituting the outermost radial flow blade ringof the turbine, and a casing providing a single volute shaped chamberencircling said outermost blade ring and receiving motive fluid dischared therefrom, said chamber having an out et and increasing incross-sectional area toward said outlet in a direction opposite thedirection of rotation of said outermost blade ring and said outermostblade ring comprising a plurality of blades each arranged tosimultaneously discharge motive fluid therefrom with an absolutevelocity having a peripheral or tangential component of flow, said flowbeing in the direction of increasing cross-sectional area of saidchamber.

5. In a radial flow elastic fluid turbine, a blade system for expandingmotive fluid comprising a rotor carrying a plurality of blade ringsincluding a blade ring constituting the outermost radial flow blade ringof the turbine, and a casing providing a volute shaped chamber having anoutlet, said chamber increasing in cross-sectional area toward saidoutlet in a direction oppositethe direction of rotation of saidoutermost blade ring and said outermost blade ring comprising aplurality of blades each arranged to simultaneously discharge motivefluid therefrom with an absolute velocity having a peripheral ortangential component of flow, said flow being in the direction ofincreasing cross-sectional area of said chamber and the direction ofabsolute dischar of the motive fluid from said blades making an angle ofat least 25 with respect to a radial line.

6. In a radial flow elastic fluid turbine, a blade system for expandingmotive fluid comprising a rotor carrying a plurality of blade ringsincluding a blade ring constituting the outermost radial flow blade ringof the turbine, and a casing providing a single volute shaped chamberencircling said outermost blade ring and receiving motive fluiddischarged therefrom, said chamber having an outlet and increasing incross-sectional area toward said outlet in a direction opposite thedirection of rotation of said outermost blade ring and said outermostblade ring comprising a plurality of blades each arranged tosimultaneously discharge motive fluid therefrom with an absolutevelocity having a peripheral or tangential component of flow, said flowbeing in the direction of increasing cross-sectional area of saidchamber and the direction of absolute discharge of the motive fluid fromsaid blades making an angle of atleast 25 with respect to a radial line.

7. In a radial flow elastic fluid turbine, a blade system for expandingmotive fluid comprising a rotor carrying a plurality of blade ringsincluding a blade ring constituting the outermost radial flow blade ringof the turbine, an inner turbine casing pro viding a volute shapedchamber having an outlet, said outermost blade ring discharging motivefluid to said chamber and comprising a plurality of blades each arrangedto simultaneously discharge the motive fluid therefrom with an absolutevelocity having a peripheral or tangential component of flow, said flowbeing in the direction of flow of motive fluid in said chamber towardthe outlet thereof, and means for securing said casing to a stationaryportion of the turbine comprising parts extending transversely of saidchamber, said parts being shaped and arranged to rovide ide vanes foraiding flow in the a oresaid irection of the motive fluid dischargedfrom said blades.

8. In a radial flow elastic fluid turbine, a blade system for expandingmotive fluid comprising a rotor carrying a plurality of blade ringsincluding a blade ring constituting the outermost radial flow blade ringof the turbine, an inner turbine casing providing a volute shapedchamber having an outlet, said outermost blade ring discharging motivefluid to said chamber and comprising a plurality of blades each arrangedto simultaneously discharge motive fluid lot therefrom with an absolutevelocity havin a peripheral or tangential component flow, said flowbeing in the direction of flow of motive fluid in said chamber towardthe 5 outlet thereof, an outer turbine casing and means for securingsaid inner turbine casing to a stationa part of the turbine supported bysai outer casin comprising a series of through bolts exten ingtransversely of said chamber, the portions of said bolts within saidchamber being shaped and arranged to provide guide vanes for aiding flowin the aforesaid direction of the motive fluid dischar ed from saidblades.

In testimony w ereof, I have hereunto affixed my signature.

ALF LYSHOLM.

